Magnesium Carbonate, Whiting, Talc as fillers


New Member
Hi all,

I've got a question about fillers. I am trying to get my canvas kayak in the water and am in a bit of a time constraint so I am thinking of filling the canvas with Zinsser 1,2,3 with added filler.

I've heard a lot of materials used as the filler and was wondering if anyone has had luck with Magnesium Carbonate. Its very cheap and easy to get hold of, but I'm wondering if its water absorbing quality is a bad thing?

On the other hand nearly every filler I've heard of (chalk, talc, silica) seems to be a desiccant, so maybe its ok? Also, would whiting or talcum powder do the same job well?

Pretty confused at this stage and would appreciate any insight.
What kind of Kayak?


Could you elaborate on the construction of your kayak? If it is one of the types where the canvas is stretched over a frame, then you probably don't need to worry about fillers. These popular kit kayaks were typically just painted with several coats of latex house paint.

If your kayak is fully planked and the canvas is supported by planking, then carry on with the fillers.
Thanks, Fitz. Yes, it is a skin on frame kayak w/10 oz duck canvas stretched over it. I'm following the George Putz book.

Putz says to mix chalk into an oil-based deck paint or to use something similar to "Interlux boat yard sanding sealer #144" which is discontinued. Anyone know if that is just any sanding sealer for wood or was that specially formulated for canvas?

If several coats of latex paint is enough to kill the weave, I guess I'll go with that.